Federal authorities have widened their misconduct investigation into the Los Angeles County jail system, demanding internal Sheriff's Department documents detailing deputies' use of force on inmates over several years, as well as other records.

Sheriff's officials balked at the size and scope of the subpoenas when they were served several weeks ago and are negotiating with federal prosecutors to reduce the number of documents they must produce.

A source familiar with the demand said it sought the names of everyone who has worked in the jails since 2009, even janitors, and whether they have been disciplined for misconduct. Federal prosecutors also sought employees' Social Security numbers, dates of birth, home addresses, phone numbers and personal email addresses.

The records demand is the first sign that federal authorities are not simply looking into several individual cases of jail brutality and other misconduct but are taking a broader look at potential wrongdoing by deputies going back years.

"I was caught completely flabbergasted," Sheriff Lee Baca said of the growing federal scrutiny of his jail system, the nation's largest. "It's like your best friend digs up your favorite rose bed."

In an interview with The Times, Baca said the subpoenaed records were so voluminous that even federal investigators "would have had difficulty ferreting through it all." Nevertheless, Baca said, the county has begun collecting the records.

Federal officials declined to comment about the subpoenas or discuss details of the investigation.

Rebecca Lonergan, a USC law professor and former federal prosecutor, said the demand for the records suggests that investigators are looking for witnesses who would be willing to cooperate as they explore whether there might be a pattern and practice of deputy misconduct in the jails.

"The question becomes whether it rises to a supervisory level," said Lonergan, who handled police misconduct cases while supervising the U.S. attorney's public corruption section in Los Angeles. "If so, it may not be just the individual deputies who are culpable. It may be supervisors all the way up to higher-ups in the Sheriff's Department."

The subpoenas come amid renewed scrutiny over the county's jail system, which has been plagued over the last decade by inmate riots, killings, the formation of a gang-like deputies clique, early release of inmates, antiquated facilities and huge legal settlements. Over the last three years, the county has paid $8.4 million to resolve claims of excessive force and failure to care for inmates, a spokeswoman for Supervisor Gloria Molina said.

Last month, The Times reported that the FBI is investigating allegations of inmate beatings and other deputy misconduct. Among the claims under review are those made by an American Civil Liberties Union jail monitor who said she witnessed deputies knock an inmate unconscious and beat him for two minutes at the Twin Towers jail...